Manufacturers of portable electrical testing and measuring apparatus are often faced with the problem of providing in their test apparatus a means for converting low battery voltages to high direct current voltages. The low battery voltages are often insufficient for operating electrical circuitry of the test apparatus or for testing the operation of equipment external to the test apparatus.
Circuitry for performing the conversion function is known. Elements commonly comprising such circuitry are a battery or other direct current voltage source, a direct current operated generator of alternating current voltage, a means for stepping up the generated AC voltages, and a means for rectifying the stepped-up AC voltage, restoring its DC character. Additionally, many such circuits provide a capacitor for filtering and smoothing the rectified voltage and for storing it for subsequent application to a load.
In addition to the DC-DC conversion feature itself, another feature that is clearly desirable is that the DC-DC conversion be performed efficiently. The DC-DC conversion means should require as little energy of the battery or direct current voltage source as possible. Efficiently operating apparatus conserves energy. With respect to battery operated portable apparatus, the inconvenience of having to replace energy storage batteries may be postponed.
Pursuant to solving this problem, previous efforts have been concerned with improving the energy efficiencies of the individual elements commonly found in DC-DC converter circuits. For example, the application of an energy efficient step-up transformer might be suggested.
Other efforts have been concerned with regulating the output of the DC-DC converter circuit relative to the applied input DC voltage. Alternatively, it has been suggested that operating parameters of the elements of the DC-DC converter may be modified based upon the detected magnitude of the converted DC output voltage.
These efforts have provided useful alternative means for conserving energy in DC-DC converter circuits whose outputs are used continuously. However, the subject DC-DC converter circuit was developed for use in portable high voltage relay operation test equipment. In such an application, the converted DC output voltage is only used infrequently and for short durations. This discontinuous use characteristic is also shared with DC-DC converter circuits, employed in portable DC high voltage breakdown test apparatus, electronic photographic flash equipment, and electrical emergency first aid equipment. For these applications, there is believed to be a need for alternative solutions to the energy conservation problem.